Thickener



Dec. 2,1 1941. A. B. SABlN 6 ,0

- THICKENER Filed June 20, 1938 3 Sheets-Sheet 1 4/ ME TOR.

A/f'rea 5. fab/n ATTORNEY.

2, 1941- A. B. SABIN 2,265,046

THIGKENER Filed June 20, 1938 3 Sheets-Sheet 2 I INVENTOR. A/fiea 5. fab/r7 ATTORNEY.

Patented Dec. 2, 1941 UNITED STATES PATENT OFFICE 2,285,046 rmcxnmn Alfred Buell Sabin, Oakland, can. Application June :0, 193:, serial no. 214,851 1 Claims. (01. 210-55 This invention relates in general to thickeners of the type wherein sludge to be thickened is fed to a tank provided at its bottom with a set of rakes by means of which the settled solids are moved to the center of the tank and from there conveyed away.

In thickeners of this type the sludge settling to the bottom of the tank oftentimes becomes so thick that it causes the mechanism to be overloaded, and therefore some means must be provided either to trip a switch in the circuit of the motor operating the rakes or to lift the rakes to a zone in which the sludg is less dense. It sometimes happens that solid matter is introduced with the sludge which forms an obstruction to the rotation of the rakes and here again means must be provided for either stopping the motor or lifting the rakes. It is preferable to raise the rakes from the sludg rather than to stop the motor and leave the rakes submerged in the thick sludge, for once the rakes have stopped rotating and are left submerged in the dense sludge, it is only with considerable difiiculty that they can be raised. Furthermore, it is the usual practice to eliminate the thickened sludge settling to the bottom of the tank downwardly through an external valve associated with the bottom of the tank. This necessitates that either the tank be supported on timbers or a suitable tunnel be provided so that access may be had to the thickened sludge outlet. Either construction is costly, for it is to be borne in mind that th tanks of these thickeners may exceed one hundred feet in diameter.

One of the objects of this invention is the provision of a thickener wherein the rakes may be lowered and raised in response to variations in the density of the sludge within the tank.

Another object of this invention is the provision of a thickener wherein the thickened sludge in the bottom of th tank may be conveyed away through an outlet extending through the bottom of the tank and provided with a valve operated from the top of the tank.

Another object of this invention is the provision of a thickener wherein the thickened sludge in the bottom of the tank may be conveyed upwardly from. the central portion oi. the bottom of th tank by a pipe depending into the bottom of the tank, thereby eliminating the necessity of the costly tunnels or timbers ordinarily used.

Another object of the invention is the provision of a thickener wherein the rake assembly is supported by a central column which in turn is secured at each end against lateral movement.

Another object of the invention is the provision of a thickener wherein the level of the rakes is determined by the density of the sludge and wherein a visible gauge is provided showing the position of the rakes and thereby indicating the load on the thickener.

Another object of the invention is the provision in a thickener of an overload device in combination with means for operating a signal and cutting oil the power.

A further object of the invention is the provision in a thickener of means for lifting its rakes when they have been locked against rotation.

Still another object of the invention is the provision or means for controlling the density of the slime discharge. a

The invention possesses other advantageous features, some of which with the foregoing will be set forth at length in the following description where that form of the invention which has been selected for illustration in the drawings accompanying and forming a part of the present specification is outlined'in full. In said drawings, one form of the invention is shown, but it is to be understood that it is not limited to such form. since the invention as set forth in the claims may be embodied in a plurality of forms.

Referring to the drawings:

Figure 1 is a top plan view of a thickener embodying the objects of my invention.

Figure 2 is a vertical mid-section of the thickener shown in Figure 1.

Figure 3 is an enlarged plan view of the rakeoperating mechanism with the top of the mechanism removed in order more clearly to show its construction and operation. It is to be noted that the device as shown in this figure has been rotated in a counter-clockwise direction through an angle of with respect to the position of the device as shown in Figure 1.

Figure 4 is a diagrammatic illustration of a slime pump attached to the center slime discharge outlet, and the operation of which may be controlled in relation to the level of the rakes within the thickener tank.

Figure 5 is a vertical section taken on the line 5-5 of Figure 3.

Figure 6 is a fragmentary vertical section taken on the line H of Figure 3.

Figure 7 is a fragmentary vertical section taken on the line 1-1 of Figure 3.

Figure 8 is a fragmentary vertical mid-section of a modification of the thickener shown in the figure above described.

As shown in Figure 1, the objects of my invention may prising a cylindrical be embodied in a thickener comtank I within which is accured at its upper edge a launder 2 o! hexagonal form by brackets 3, or any other type or launder. Supported on the upper periphery oi the tank I and secured thereto in any suitable manner is a pair or spaced parallel I beams 4 and 5 disposed on either side of a diameter the tank. The I beams 4 and are reiniorced by trusses 8 and support cross members 1 and 8 which is shown may be I beams or any other suitable shapes. Seated on the cross members 1 and 8 and secured thereto by ears 9 is a ring II, the upper periphery of which is provided with an outwardly extending flange I2. Formed integral with the ring II is an inwardly extending ball race I3 having a depending skirt I4. RotatabIy supported on ball bearings I5 accommodated on the ball race I3 is a turntable or pan I9 provided with an upwardly extending central collar I1. The pan I8 carries two sets of diametrically opposed pulleys I9 and I9 and I8a and I9a, the pulleys l8 and I9 being Journaled on pins 2| and 22 threaded in the base oi said pan, and the pulleys I81: and I9a being similarly carried by pins not shown. Journaled about the collar I1 is a worm .wheel 23 adapted to be driven by a worm gear 24 keyed to a shaft 25. The shaft 25 extends through a housing 28 formed integral with the ring II and is connected with one end of flexible coupling 21. The other end or the coupling 21 is secured to a shaft 28 driven through a speed reducer 29' by an electric motor 30. Journaled about the shaft 29 is a hand operated clutch 29a, arranged for engagement with a complementary clutch member 21a carried by the coupling 21. The motor 39 and its associated speed reducer 29 are supported on a bracket 3I secured the ring II. Depending Irom and iormed .integral with the worm wheel 23 is a pair of diametrically opposed lugs 32 and 33, the lower ends of which are co-planar with a plane passing through the pulleys I8 and I9 and I91: and I9a.

Bolted to the flange 34 provided with an upwardly extending threaded flange 35 and with downwardly extending circular flanges 38 and 31. Accommodated within the downwardly extending circular flange 38 and bolted to the cap 34 is an inwardly threaded fltting 38 to which is secured a pipe 39 extending downwardly through the collar I1 and terminating in a foot 4I adjacent the bottom of the tank I, as best shown in Figure 2. The foot H is provided with a number of spacers 42 for maintaining the lower end of the pipe 39 in spaced relation with the bottom 01' the tank, thereby permitting the egress oi the thickened sludge from the bottom or the tank.

Bolted to a central hub 43 oi the pan I8 is a ring 44 to which is welded a torque tube or sleeve 45, the lower end of which terminates at a point immediately above the foot 4| of the pipe 39 and is provided with a wiper mechanism 48 tor maintaining the zone immediately adjacent the lower end of the pipe 39 free and clear of any obstructions. 1

Extending over the upper edge of the tank I intermediate the I beams 4 and 5 is a slime teed pipe 41, the inner end of which terminates immediately above a distributor ring 48 provided with a perforated bottom 49 and which is secured to the sleeve by a set screw 5I passing through an upwardly extending sleeve 52.

Secured to each of the lugs 32 and 33 of the I2 of the ring II is a cap in any desired manner to v worm wheel 23 are chains 53 and 54 which respectively pass over the pulleys I9 and I9 and then over pulleys 55 and 59 Journaled within recesses 51 and 59 formed in the hub 43 of the pan I8. The chains 53 and 54 then pass through pipes 89 and 8I respectively secured within openings formed in the bottoms oi the recesses 51 and 58, and are secured at their lower ends to a ring 82 Journaled about the tubular sleeve 45.

Suspended from the ring 82 by rods 83 and 84 are rakes 95 and 88, the inner ends of which are secured to a yoke 81 Journaled on the sleeve 45. Surrounding the sleeve 45 is a spring 88, the upper end oi which is accommodated within a portion 01 the ring 48 extending beneath the perforated bottom 49, while its lower end is supported on a plate 89 secured to the ring 82. Clamped to the sleeve 45 is a collar 1| to which are threaded radially extending arms 12 and 13. To the outer ends of the arms 12 and 13 are secured rods 14 and 15, the lower ends of which are connected to the rakes 85 and 98.

Threaded to the upper end of the collar I1 is a ring gear 18 adapted to mesh with tour pinions 11, equally spaced about its periphery. Each of the pinions is secured to a sleeve 18 in threaded engagement with a ring 19, and each of the threaded sleeves 19 is mounted for rotation on a pin 8I secured to the ring gear 29. Passing through the ring II at a point above the housing 28 (Figures 3 and 5) is a rod 82. to the inner end of which is secured a lever 83 carrying a set screw 84 adapted to engage the ring 19 (Figure '1). The outer end of the rod 82 carries a pointer 85 adapted to move over a graduated scale 88 secured to the housing 28.

As diagrammatically shown in Figure 4, the pointer 95 and scale 89 may be constructed in the form of a rheostat for controlling the power input to a motor 81 which in turn operates a slime pump 88 by which slime is removed from the tank I.

Surrounding the periphery of the pan I8 is a brake band 9| operated in any suitable manner by a hand wheel 92 carried by a rod 93 threaded to a bracket 94 secured to one end of the housing 28. Although not shown in the drawings, one end of the brake band is made last while the other end is secured directly or indirectly to the inner end of the rod 83 so that upon rotation of the hand wheel 92, pressure may be applied as desired by the brake band 9I on the brake shoe formed by the periphery of the pan I8.

A seal between the ball race I3 and the pan I8 may be made by a packing 85 so that the oil used to lubricate the movable members enclosed within the chamber formed by the ring II and the pan I8 may be prevented from reaching the bearings. Formed in the cap 34 is a man hole 98 provided with a cover plate 91. Threaded to the flange 35 is a sludge discharge pipe 99. Supported on the I beams 4 and 5 is a board walk 99 which in accord with the usual practice is provided with guide rails IIII. Passing through the upper edge of the tank I is an overflow discharge pipe I92 communicating at its inner end with the bottom of the launder 2.

The device as above constructed operates as follows:

Slime is fed to the tank I by gravity or by a pump through the slime feed pipe 41 and the distributor ring 49. When the slime has reached the desired level in the tank I, the electric motor 38 is put into operation and through the speed reducer 29, flexible coupling, and the worm gear 24, rotates the worm wheel 23. The worm wheel 23 rotates about the collar II, thereby placing the chains 63 and 54 carried by the lugs 32 and 33, under tension. Since the weight of the rakes 65 and 66 is carried by the chains 53 and 54, the rotary movement of the worm wheel 23 will be imparted through the pulleys I8 and I3 to the pan I6 and consequently the rakes, the sleeve 45, the pan I6, and the worm wheel 23 will rotate as a unit. If, however, the density of the sludge within the zone in which the rakes 65 and 66 are operating is above a predetermined value, the rotary motion or the rakes will be resisted and as a consequence the pan I6 to which the pulleys I8 and I! are secured, will be held against rotation and there will be relative rotary motion between the pan I6 and the worm wheel 23. This relative motion between the pan I6 and the worm wheel 23 will cause the chains 53 and 54 to move upwardly over the pulleys 55 and 56, thereby bodily lifting the rakes against the action of the spring 66 and gravity. The action of the spring 66 is obviously the equivalent of weighting the rakes and in some instances it might be desirable not only to eliminate the spring but even to buoy the rakes. It is to be noted, however, that the spring produces a variable load whereas gravity produces a constant load. The higher the rakes are lifted, the greater will be the compression on the spring 68, tending to force the ring 62 downwardly. The density of the slime within the tank I increases with depth, and therefore normally a zone will be reached during the upward movement of the rakes at which the density of the slime is insufficient to further retard the rotation of the rakes and at this point the rakes, the sleeve 45, the pan I6, and the worm wheel 23 will again rotate as a unit. Conversely, if the density of the sludge in which the rakes are operating is insufilcient to maintain this balance, the weight of the rakes reinforced by the action of the spring 68, will force the rakes downwardly into a lower zone and in so doing there will again be relative rotary motion between the pan I6 and the worm wheel 23, until a balance is again struck. Obviously, any solid obstruction within the zone in which the rakes are operating and which is sufilcient to retard or stop their rotary motion will cause the rakes to rise in the same manner as a slime of excessive density.

Due to the fact that the ring gear I6 is secured to and rotates with the pan I6, and that the pinions I1 are carried by the worm wheel 23, any relative rotary motion between the pan I6 and the worm wheel 23 which as above explained causes a vertical movement of the rakes, will cause the pinions ll to rotate, and thereby, due to the threaded engagement of the sleeves [6 with the ring 19, will cause the ring I9 to rise or fall. The vertical movement of the ring I3, as best shown in Figure 7, will cause the rod 82 to rotate, thereby producing a movement of the pointer 85 over the scale 86. The-positin of the pointer 85 on the scale 66 can therefore be made to indicate the level of the rakes and the density of the sludge in which they are operating. Furthermore, if as shown in Figure 4 the pointer 85 and the scale 86 are made in the form of a rheostat to control the feed pump 68 through the operation of the motor 61 or to control the slime discharge of tank I, it is apparent that the rise and fall of the rakes may be made to maintain automatically a substantially constant slime density within the zone in which the rakes are operating.

The rakes 65 and 66 operate. in a normal manner to move the thickened sludge in the bottom of the tank to the center thereof, from whence it is discharged upwardly through the pipe 33 and the pipe, to a further stage in the process, such as filtration. The supernatent liquor overflows the lower lip of the launder 2 and passes through the overflow discharge pipe I02 to any subsequent step in the process. By discharging the thickened sludge upwardly through the pipe 39 instead of through a pipe extending downwardly through the bottom of the tank, I have made it possible to support the tank directly on the ground without the usual requirement of either providing costly tunnels or supporting the tank on timbersso that there may be access to the sludge discharge pipe extending downwardly through the bottom of the tank as ordinarily used. Bearing in mind that thickeners of this type may exceed one hundred feet in diameter, the elimination of such tunnels or timbering is a decided advantage.

It is to be particularly noted that the weight of the rakes 65 and 66 is carried by the chains 53 and 54 through the ring 62 and that the torque developed in rotating the rakes is carried through the arms I2 and I3 by the sleeve 65.

If it is for any reason desired to lift the rakes 65 and 66, an artificial torque may be placed on the pan I6 by the brake band 9! so as to hold the pan against rotation, whereupon rotation of the worm wheel 23 will cause the rakes to be lifted as above described. Although the worm wheel 23 is normally driven by the motor 36, it may be rotated by hand simply by engaging the hand clutch 28a with the complementary clutch member 21a carried by the coupling 21.

Although as herein described and illustrated in the drawings, the rakes are moved bodily in response to any relative rotation between the pan I6 and the worm wheel 23, the rakes 65 and 66 may if desired be hinged to the yoke 61 with the result that relative motion between the pan I6 and the worm wheel 23 will cause only the outer ends of the rakes to move vertically. 0bviously, cables may be substituted for the chains 53 and 56, and in the following claims the term chain" shall be deemed to include a cable or other equivalent device. Likewise the function of the pulleys l6, I8a, I3, and I 9a may be performed by a single grooved ring rotatably mounted on the turntable or pan I 6 and provided with suitable notches for the downward passage of the chains 53 and 56.

In Figure 8, the tank 8 is provided with a central sludge sump IIIl provided with a downwardly extending sludge outlet II! and an upwardly extending flanged fitting II2, adapted to be secured to the pipe 33. The fitting H2 is formed with openings II 3 for establishing communication between the sump and the interior of the fitting and with interior ribs I I 4 to which is slidably keyed a valve H5. The valve I I5 is carried by the lower end of a small pipe II6 extending upwardly through the pipe 39 and which may be conveniently used for the introduction of water or air for cleaning the valve and sludge outlet. To the upper end of the pipe II6 is threaded a hand wheel Ill supported on a. plug H8 screwed in the flange 35. As a result of this construction, it will be seen that the valve H6 maybe operated from the top of the tank by simply turning the hand wheel Ill, and that although the thickened sludge is discharged through the bottom of the tank again, no tunnels or supporting timbers are required, for the valve is accessible from within the tank. If it mounted in said tank for rotary movement about a vertical axis; pulleys secured to the upper portion of said tube; a driven member mounted in said tank for rotation about the upper portion of said tube; chains secured to said driven member and arranged to pass over said pulleys and downwardly along said tube; and a rake suspended irom said chains and arranged for rotary movement about the axis oi'said tube and for vertical movement along said tube.

2. A thickener comprising: a tank; a column mounted vertically within said tank; a vertical frame circumscribing and free to rotate about said column; pulleys fixed to the upper portion of said vertical frame; a driven member mounted within said tank adlacent said pulleys and tree to rotate about said vertical frame; chains secured to said driven member and arranged to pass over said pulleys and downwardly along said tube; and a rake supported from said chains.

3. A thickener comprising: a tank; a vertical tube rotatably supported within said tank; a set oi horizontally disposed pulleys and a setof vertically disposed pulleys carried by said tube; a gear supported by said tube above said pulleys and free to rotate with respect thereto; chains passing over said pulleys and secured at-their upper ends to said gear; rakes supported from said chains; means for transmitting rotary movement or said tube to said rakes; and means for driving said gear.

4. A thickener comprising: a tank; a vertical tube rotatably supported within said tank; a set of horizontally disposed pulleys and a set 01 vertically disposed pulleys carried by said tube; a gear supported by said tube above said pulleys and i'ree to rotate with respect thereto; chains passing over said pulleys and secured at their upper ends to said gear; rakes supported from said chains; means for transmitting rotary movement oi said tube to said rakes; means for driving said gear; a ring gear secured to said tube; spaced pinions mounted on said gear arranged to mesh with said ring gear; screws mounted on said pinions for rotation therewith; a ring concentric with said tube and in threaded engagement with said screws; and means responsive to the vertical travel of said ring gear for indicating the level of said rakes.

5. A thickener comprising: a tank provided along its bottom with a sump; a slime discharge pipe external to said tank and communicating with said sump; a rake assembly including radially disposed rakes rotatably mounted within said tank; a conduit extending along the vertical axis of said rakes with its lower end in registration with said pipe and in open communication with said sump; a valve for cutting of! communication between said sump and said pipe; and means extending through said conduit for operating said valve from the top of said thickener.

6. A thickener comprising: a tank provided along its bottom with a sump; a slime discharge pipe external to said tank and communicating with said sump; a rake assembly including radially disposed rakes rotatably mounted within said tank; a conduit extending along the vertical axis of said rakes with its lower end in registration with said pipe and in open communication with said sump; a valve for cutting of! communication between said sump and said pipe; and a pipe extending through said conduit for operating said valve from the top of said thickener and for introducing a cleaning fluid to said valve.

'1. A thickener comprising: a tank; a driven gear arranged for rotation within said tank about a vertical axis; a member concentric with said gear and arranged ior'reiative rotation with respect thereto; pulleys fixed to said member; chains secured to said driven gear and arranged to pass downwardly over said pulleys; a rake supported from said chains; 9. scale associated with said thickener and having no relative movement with respect thereto; a pointer arranged to sweep over said scale; and means responsive to relative rotation between said gear and said member for actuating said pointer.

ALFRED BUELL SABIN. 

